Acta Crystallographica Section D

Biological Crystallography

Volume 70, Part 2 (February 2014)


research papers



Acta Cryst. (2014). D70, 253-260    [ doi:10.1107/S1399004713026680 ]

Weak data do not make a free lunch, only a cheap meal

Z. Luo, K. Rajashankar and Z. Dauter

Abstract: Four data sets were processed at resolutions significantly exceeding the criteria traditionally used for estimating the diffraction data resolution limit. The analysis of these data and the corresponding model-quality indicators suggests that the criteria of resolution limits widely adopted in the past may be somewhat conservative. Various parameters, such as Rmerge and I/[sigma](I), optical resolution and the correlation coefficients CC1/2 and CC*, can be used for judging the internal data quality, whereas the reliability factors R and Rfree as well as the maximum-likelihood target values and real-space map correlation coefficients can be used to estimate the agreement between the data and the refined model. However, none of these criteria provide a reliable estimate of the data resolution cutoff limit. The analysis suggests that extension of the maximum resolution by about 0.2 Å beyond the currently adopted limit where the I/[sigma](I) value drops to 2.0 does not degrade the quality of the refined structural models, but may sometimes be advantageous. Such an extension may be particularly beneficial for significantly anisotropic diffraction. Extension of the maximum resolution at the stage of data collection and structure refinement is cheap in terms of the required effort and is definitely more advisable than accepting a too conservative resolution cutoff, which is unfortunately quite frequent among the crystal structures deposited in the Protein Data Bank.

Keywords: diffraction data resolution limit; data-quality criteria; nominal resolution; optical resolution.


pdfdisplay filedownload file

Portable Document Format (PDF) file
[ doi:10.1107/S1399004713026680/tz5036sup1.pdf ]
Supplementary material


Notes:

To open or display or play some files, you may need to set your browser up to use the appropriate software. See the full list of file types for an explanation of the different file types and their related mime types and, where available links to sites from where the appropriate software may be obtained.

The download button will force most browsers to prompt for a file name to store the data on your hard disk.

Where possible, images are represented by thumbnails.

 bibliographic record in  format

  Find reference:   Volume   Page   
  Search:     From   to      Advanced search

Copyright © International Union of Crystallography
IUCr Webmaster